What it is doing is at the 2-3 upshift (I believe) the RPM's jump 300 or more, you feel the slight loss of forward acceleration, then the rpm ramp back down while it completes the shift and full acceleration (power) returns with a slight surge. It simply seems like a slipping clutch that is slow to fully engage.

What say you?

A. It sounds like you have a definite slip between second and third gears. If this is the only shift that it slips on, the problem is internal to the transmission.

There is an adjustment to the low-intermediate servo apply rod so a simple adjustment could fix the problem.

If it were your transmission rebuilt in the shop, and they took apart the valve body, there may have been one or more check balls inadvertently left out. Or there may be a sticking valve in the valve body.

Less likely, the transmission oil pump pressure may be too low or the Electronic Pressure Control (EPC) solenoid is not working or damaged.